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Re: [TenTec] Tentec 700 Hand Mic Question

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Tentec 700 Hand Mic Question
From: Bwana Bob <wb2vuf@verizon.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 18 Dec 2010 12:26:49 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>

Did you try rewiring the mic element so that it is powered all the time? 
Maybe the mic power is going through the PTT switch and the turn-on 
transient is putting out an audio pulse.


                 Bob WB2VUF

On 12/18/2010 10:50 AM, K8JDC wrote:
> Friends,
>       I recently got a Tentec 700 hand mic and noticed that it causes the
> radio to transmit a spike every time the PTT lever is pushed.  The mic
> was set up to use a 9V battery when I got it but I have wired it to
> operate directly off my Paragon II.  It spikes on either power source
> and the spike is basically full output power so it's a bit alarming.
>       I originally thought the spike was related to the operation of the
> PTT switch...i.e. a little clicking noise causing the spike but that's
> not true.  If I key the PTT with the mic disconnected from the radio and
> then connect the mic to the radio, the spike still happens so it appears
> that it is related to applying the voltage to the mic circuit or
> cartridge.  I played around a bit trying to add a capacitor to stabilize
> the power in the circuit and eliminate any transients but the spike is
> still there.
> Has anybody seen this and/or have a fix?  The existing caps in the
> circuit appear to be okay (i.e not shorted) and I think the cartridge
> itself is the cause of the spike.  There is a resistor feeding power to
> the cartridge but I have not tried raising the value (yet).
> Thanks...
> Dave
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